Prevalence of Histoplasma capsulatum at Bird Roosting Sites Compared to Non-bird Roosting Sites

Indianapolis, IN

States along the Ohio River Valley and Mississippi River are known to have a higher prevalence of histoplasmosis than other regions in the United States. The causative fungal pathogen, Histoplasma capsulatum is a polymorphic organism showing mycelial and yeast-like phases of growth. It is particularly found in bird and bat roosting sites and other places where birds and bats are heavily populated. Histoplasma capsulatum is dispersed when the contaminated soil is disrupted. The objectives of this study are to determine whether H. capsulatum is more prevalent at bird roosting, feeding, and nesting areas compared to areas where birds are less concentrated. Eight sites were selected for the study: 5 birdfeeders, 2 nesting sites, a horse pasture, and an adjacent treeline. Soil sampling took place from August 12 -September 30, 2017. A total of 50 soil samples were collected, (29 experimental and 21 control sites) cultured on rose bengal agar with streptomycin, and incubated for 3 weeks at 30oC. Twelve morphologically distinct types of colonies grew in culture from the soil samples (range: 1-8 colony types per sample). Histoplasma capsulatum was not identified for any samples, therefore results were inclusive.